Predetermined torque release socket wrench



Dec. 15, 1953 o. B. HARMES PREDETERMINED TORQUE RELEASE SOCKET WRENCHFiled April 28, 1952 Bill E Patented Dec. 15, 1953 UNIT E D1.- STATESPATENT E F 1 CE PREDE-TERMINED' TORQUE RELEASE SOCKET. WRENCH Oren B.Harmes; Algona, Iowa, assignor to LivingstonToolt 00., Algona, Iowa, a.partnership Application April.2,8,. 1952, SerialINO. 284,781

8 Claims;

This invention relates to: torque wrenches. More particularly, itrelatesto wrenches for-automatically releasing themselves when a predetermined high torque is exerted thereupon.

This invention is an improvement'on my invention entitled Torque Wrenchfiled by me April- The torquewhereupon only a small" or moderate amountof torque is to be exerted. My present invention as disclosed andclaimed herein constitutes an improvement upon my invention disclosed inmy previous application with respect to torque wrenches in general andmore especially"- with respect totorque wrenches constructed and to beused for imposing ahigh torque upon the elements to be turned thereby;

Various wrenches have been constructed previously for the purpose ofapplying a'torque to an element to be turnedand some of these areautomatically releasable: None of these, however; to the applicants'knowledge; are adapted for applying a high torque to the element to beturned and to automatically release itself when a predetermined hightorque is applied to thatelement. All of the automatically releasingtorque wrenches knownto the applicant prior to the instantinvention areadapted solely for usewith small-L tomoderate amounts of torque.

It is" a general object of my invention to provide a novel and improvedtorque wrench of cheap and simple construction.

A. more specific object is to provide'anovel and improved torque wrenchwhich will require ahigh torque before it automatically releases.

Another object is to provide a torque wrench requiring hightorquefor'its release and in which adjustment may be made to causethewrench to release at any desired predetermined high torque:

Another object is to: provide anovel and improved: high torque wrench ofcompact size and capable of ready adjustment to release at otherpredetermined high torques. 7

Another object is to: provide a high torque wrench. which may bequickly: and; easily reset after its release.

These and other: objects and advantages of my invention. wiil. morefully appear from thefoilowing description. made in connectionwith theaccompanying drawings; wherein like reference characters refer.tosimilar parts through out. the several views;. and. in which:

Fig. l is a longitudinal sectional View of one embodiment of myinvention with a portion of the handle broken away;

Fig. 2 is a fragmentary side elevational view of the same with the headmember shown in longitudinal section taken in a plane at right angles tothe plane shown in Fig. l; and

Fig. Bis a top plan view of the head member with the top plate intactand of the interior shank portion of the handle.

One embodiment of my invention may include, as shown in Figs. l-3, aninteriorly tapped handle member indicated generally as H and havingrigidly secured thereto at its outer end a head member 6. The headmember 6- lras a hollowed out portion 1 formed therein, this hollowedarea beingsomewhat elongated but generally circular at each of its endportions as best shown in Fig. 1 and indicated by thenumeral 3. Anopening Ba is formed in the bottom wall of the hollowed out head memberso that a passage extends transversely through the head member 6. Thisis best shown in Fig; 2. A second opening 8b is formed in the-bottomwall to receive a pivot pin to be-hereinafter described. Mounted forrotation in the outer end portion of the head memher is a rotatable bodyor socket 9. This socket 9 has an opening It extending therethrough ofthe proper size" and shape to engage the element' desired to be turnedby the wrench. The socket 9 has a central circumferential rib H whichprovides a shoulder 52 to cooperate with the portions Iii of the bottomwall which define the opening 8a tohold the socket from slidingoutwardly from the head member 6.

A plate M is secured to the other side of the head member by cap screwsi5, this plate having anopening I6 therein. of suificient size to permitthe outer edge portions of the socket to extend outwardly therethrough.A smaller opening M's. is also: formed in the plate it to receive thepivot pin previously referred to and to be hereinafter described; Formedin the outer circumferential surface of the central rib ii of the socketii are a plurality of" ratchet teeth it which are directed in a generaldirection around the socket member (this direction being shown asclock-wise in Fig. 1). Absent any engaging element-cooperating withthese ratchet teeth ['5 the socket ii -is free to rotate: in the hollowportion a of the'head' member but is confined to that portion.

The handle H is comprised of a shank it which, as shown in Fig. 1, isformed integrally with the head member 6. This shank l8 has alongitudinally extending-bore 19 which communicates with the hollowedout portion 7 of the 3 head 6 and which extends throughout the entirelength of the shank. The medial portion of the shank I8 is externallythreaded as at 20 while the rearward or inward portion is reduced as at2|. The extreme inner end of the shank I8 is provided with a pair ofinwardly extending shoulders 22 which are disposed opposite each otheras best shown in Fig. 1 and Fig 3. The shank I8 is graduated as at 23along the circumferential surface of its outer end portion.

The other section of the handle H is internally threaded as at 24 tocooperate with the external threads 20 of the shank Is as best shown inFig. 1. This section has an interior bore extending inwardly from itsouter end and of suflicient diameter to accommodate the shank 18. Thebore is of suiiicient length to also accommodate a relatively strongspring 25 which is maintained at its inner end in central position withrespect to the bore by a plug 26 having a reduced head 21 adapted to beinserted within the spring. Also formed in this section of the handle isa readin hole 28 which, when the two sections of the handle are threadedtogether, moves directly opposite the graduations at 23 on the shank Hi.This section also has an internally threaded aperture 29 adapted toreceive a set screw 30 opposite the reduced portion 2| of the shank l3.Mounted for limited sliding movement within the shank H! of the handle His a rod 3| as best shown in Fig. 1. The inner end of this rod isexternally threaded as at 32 to threadedly receive a nut 33 of externaldiameter equal to the spacing between the opposed shoulders 22. As bestshown in Fig. 1, this rod 3| is of sufficient length so that its innerend extends inwardly beyond the shank I8 and a nut 33 is received at theouter end of the spring 25 and is of sufficient length so that its outerend 34 extends into the hollowed out area of the head member 6.

The outer end of the rod 3| is flattened and reduced as at 35 to receivethe inwardly extending bracket arms 36 of a toggle member indicatedgenerally as T. The bracket arms 36 are spaced from each other toaccommodate the flattened portion 35 therebetween and have aperturesformed therein to accommodate a pivot pin 31 which extends through eachof the arms 36 and the flattened portion 35. This pivot pin 31 isarranged to extend transversely with respect to the rod 3| and on anaxis substantially parallel to the axis of rotation of socket member 9.

The toggle member T is provided with an outwardly extendingcircumferential shoulder 38 and is further provided at its outer endportions with a cylindrically shaped key 39. This key 39 extendstransversely with respect to the rod 3| and substantially parallel tothe pivot pin 31. A relatively weak spring 43 is carried by the outerend 34 of the rod 3| and by the inner end of the toggle member T. Thisspring abuts against the shoulder 38 and against the wall of the headmember which defines the hollowed area 1. The walls of the hollowed areai are suliiciently spaced from the toggle member T so that the lattermay swing sufficiently far to either side of the longitudinal center ofthe rod 3| to cause the key 33 to become completely disengaged from thelever member to be hereinafter described.

Pivotally mounted between the bottom wall of the head member 3 and theplate I 4 upon a pivot pin 4| is a lever member indicated generally as42, this lever member being in the form of a dog. The pivot pin 4| ispivotally mounted for free pivotal movement in the openings 8b and |4aof the bottom wall and top plate l4 respectively. A reset arm 43 extendstransversely to the pivot pin 4| and outside the bottom wall of the headmember. This lever member or dog 42 has a tooth 44 of suflicient lengthso as to engage the teeth I! of the rotatable body or socket 9. Itsopposite end portion has a recess 45 formed therein and is adapted toengagingly receive therein the key 39. This recess 45 is so positionedthat when the recess is to one side of the longitudinal center of thehandle H the toggle T is also swung to that side. This can best be seenin Fig. 1. It should be noted that the lever member 42 actuallyconstitutes a lever with the fulcrum 46 being at the center of the pivotpin 4|, the shorter lever arm being that portion 01 the lever or dogwhich carries the tooth 44 and the longer lever arm being that portionof the dog which carries the recess 45.

When the wrench is assembled for use the respective parts are in therelation to each other as best shown in Fig. 1. By referring to Fig. 1it can be seen that the section of the handle which receives the shankportion I8 is threaded onto the shank sufliciently far to exert thedesired compression on the spring 25. When this has been done the setscrew 3|] is tightened and thereafter the socket 9 will be preventedfrom turning by the toggle T and the lever arm 42 until a sufficientlyhigh torque has been exerted thereon to cause the toggle T to cam overand the lever arm 42 to pivot about its fulcrum 46 to the dotted lineposition shown in Fig. 1, thereby compressing the spring 25. It can bereadily seen that in normal position the toggle T extends diagonallywith respect to the rod 3| and is constantly urged toward engagingrelation with respect to the lever arm 42. It can also be readily seenthat the lever arm 42 extends diagonally with respect to the rod 3| butin the opposite direction to the direction in which the toggle member Textends and is constantly preventing the socket member 9 from rotatingin the direction in which its teeth I! extends. At the same time thespring 25 constantly urges outwardly against the nut 33 to tend toprevent the rod 3| from being moved inwardly and to simultaneously, ofcourse, tend to prevent the toggle mechanism T and the lever member 42from swinging over to disengaging position shown in broken lines in Fig.1.

In operation, the wrench is arranged so that the socket 9 will engagethe bolt, nut, pin or other element desired to be rotated. The necessarytorque is then applied to the handle H to rotate the elements. So longas the resistance offered by the element being turned does not exceed apredetermined torque arrived at by the amount of compression placed uponthe spring 25 and the purchase obtained through the use of the lever arm42 and the toggle mechanism T, the wrench will continue to tighten theelement. This amount of torque will necessarily be relatively highbecause the amount of purchase attained through the use of the levermember 42 is so great as to require an unusually high amount of torqueto cause the toggle T to swing over to disengaging position. However,when this predetermined torque is exceeded the toggle T will cam over tothe opposite side and in so doing will compel the rod 3| to moveinwardly, overcoming the outward thrust of the spring 25. By cammingover, the toggle T automatically, for all practical purposes, causes thelever member 42 to release the socket 9 since a much lower torque willbe required to cause the socket to rotate relative to the tooth 44 whenthe tooth is swung to the position shown in broken lines in Fig. 1. Thusit can be seen that the socket member 9 is free to rotate relative tothe handle H after the toggle T has swung to the broken line position.

After the toggle T has cammed over, the wrench can be immediately resetfor use on the next element by swinging the reset arm t3 back to itsoriginal position, thereby causing the longer lever arm of the levermember 42 to thrust the toggle mechanism T back beyond its originalposition until the key 39 can again slip into the recess 15. When thisis done the tooth member 4 3 will again beengaging the ratchet teeth iiof the socket member 9 and the wrench is again ready for use.

The torque required to cause the toggle T to cam over may bepredetermined at various degrees of compression exerted on the spring 25and the same may be indicated on the shank it by graduating the shank asindicated in Fig. 3. Thus the user may readily adjust the compressionexerted on the spring 25 by tightening or loosening the portion of thehandle carrying the set screw with respect to the shank in. When thehandle has been adjusted so that the desired torque will be required tocause the toggle T to cam over, that fact will be indicated by referenceto the reading opening 28 as shown in Fig. 2. Thus it is possible toadjust the wrench readily to cam over at various predetermined torques.

Thus it can be seen that it becomes impossible with this Wrenchregardless of carelessness or adjustment in the use of wrenches totighten a given element beyond a predetermined high torque for thesocket 9 will automatically be released as soon as that predeterminedtorque is exceeded. At the same time it is possible to tighten elementswhich require a high torque and yet to have the automatic releasefeature available. In other words, it is now possible, through the useof my wrench, to tighten a given element to a high degree of torque withfull assurance that when that torque is reached there is no danger ofexceeding the same.

It should be noted that my wrench is also adjustable to compensate forchanges which may take place over a period of time in the resistancewhich the spring 25 offers to compression. By adjusting the nut 33 onthe thread end of the rod 3| the amount of compression can be changedeven though the two sections of the handle remain in the same positionwith respect to each other.

It should be noted that I have provided a torque wrench which is cheapand simple to construct and which may be quickly and easily reset afterits release. My torque wrench is constructed to exert a high torquepreviously impossible in torque wrenches and to automatically releasethis torque when a predetermined limit is reached. This positivelyprevents the element being tightened by the wrench from being damagedseriously. It is highly important in various assembling operationswherein the particular material being used is of such a nature as torupture when a predetermined torque is exceeded. My wrench provides aready and eiiicient means for accomplishing this function. For example,it is imperative today in the installation of spark plugs that the plugsbe inserted with a high torque in order to insure long life of theplugs. When the plugs are installed merely through guessing at theamount of torque applied thereto there is constant danger that eitherinsufficient torque will be used or that the plug itself will be damagedby an excess of torque being applied thereto. My wrench positivelyprevents the occurrence of such damage or improper installation andenables even the most unskilled type of laborer to install spark plugsat the optimum torque.

It should also be noted that my wrench, despite the fact that it ispossible of exerting unusually high torque upon a given element and iscapable of automatically releasing when a predetermined high torque isattained, is very compact and rela tively simple to manufacture. Inspite of its simplicity, compactness and inexpensiveness, it is a highlyefficient tool which takes the risk out of tightening elements to a hightorque because the element of guess-work is completely removed.

It will, of course, be understood that various changes may be made inthe form, details, arrangement and proportions of the various partswithout departing from the scope of my invention.

What is claimed is:

1. An automatically releasing torque wrench comprising a handle member,a rotatable body mounted for free rotation upon said handle memberadjacent one end thereofand adapted to be connected to the element to beturned by the wrench, a movable lever member carried by said handlemember adjacent said rotatable body, a portion of said lever memberengaging said ro tatable body to ordinarily prevent its rotation,

and resilient mechanism normally urging said portion of said levermember in a predetermined direction about its fulcrum to yieldably holdsaid rotatable body against rotation in the opposite direction so longas a predetermined torque is not applied thereto, said portion of saidlever member being swingable into non-engaging position relative to saidrotatable body when such predetermined torque is applied to saidrotatable body to permit the latter to thereafter turn without beingre-engaged by said portion or" said lever.

2. An automatically releasing torque wrench comprising a handle memberhaving a head portion at one end thereof, a rotatable body mounted forfree rotation upon said head portion of said handle member and havingoutwardly extending teeth on the outer circumferential surface thereofand adapted to be connected to the element to be turned by the wrench, amovable lever member carried by said handle member adjacent saidrotatable body, a portion of said lever member engaging said teeth ofsaid rotatable body to ordinarily prevent its rotation, and resilientmechanism normally urging said portion of said lever member in apredetermined direction about its fulcrum to yieldably hold saidrotatable body against rotation so long as a predetermined torque is notapplied thereto, said portion of said lever member being swingable intonon-engaging position relative to said rotatable body when suchpredetermined torque is applied to said rotatable body whereby said bodywill thereupon become freely rotatable relative to said handle memberwithout being re-engaged by said portion of said lever.

3. An automatically releasing high torque wrench for applying a hightorque to an element 1 to *b-turned, said ;wrench' comprising a handlemember having a head portion thereupon; a rotatable body mounted forfree rotation upon said head portion of said handle member and. adaptedto be connected to the element to be turned by the wrench, a movablefirst-class lever member carriedby said handle member. adjacent saidrotatable body and having a longer lever armand a lever member, aportion ofsaid lever member engaging said: rotatable bodyto ordinarilyprevent" its. rotation, and resilient means normally urging said portionof said lever arm in a predetermined direction' about its fulcrum toyieldably-hold said rotatable body against rotation in the oppositedirection so long asa predetermined torque is not applied thereto, saidresilient means including toggle mechanism extending normally diagonallyto saidlever member and engaging the longer leverarm of saidlever'member to insure that said rotatable member will not be permittedto rotate until a predetermined high torque is applied thereto, saidshorter lever arm being swingable into non-engaging position relative tosaidbody when such apredetermined high torque is appliedto said body to.permit the latter to thereafter turn without being re-engaged by saidportion of said shorter lever. arm.

4. An automatically releasing torque wrench comprising a handle memberhaving a head por tion at one end thereof, a rotatable body mounted forrotation upon said head portion of said handle member and adapted to beconnected to the-element to be turned by the wrench, a movablefirstclass lever member carried by said handle memberandpivoted at itsfulcrum adjacent said, rotatable body, the shorter end portion of saidlever member engaging said rotatable body to ordinarily prevent itsrotation, a rod slidably mounted within said handle member,togglemechanism connected to one end of said rod and normally extendingdiagonally thereto and engaging the longer end portion of said levermember and normally urging the'same in a predetermined direction, andresilient means normally causing said toggle mechanism to urge saidlonger end portion of said lever member to-move in a predetermineddirection about its fulcrum to yieldably hold said rotatable bodyagainst rotation in the opposite direction so long as a predeterminedhigh torque is not: applied thereto. 1

5. An automatically releasing high torque wrench for use in applying ahigh torque to an element to be turned, said wrench comprising a handlehaving a head member at one end thereof, a rotatable bodymounted forrotation upon said head member of said handle and adapted to beconnected to the element to beturned by the wrench, a first-class levermember movable about its fulcrum and carried by said handle adjacentsaidrotatable body, said lever member comprising a dog pivotally mountedat its medial portion uporrsaid headmember and-having a-longer leverarm; and a shorter lever, arm, the shorter lever arm of; saiddogengaging said Wrench body to ordinarily prevent its rotation, and thelonger lever arm of said dog having a recess formed therein, a shankslidably mounted within said handle, toggle mechanism positivelyconnected to one end. portion of saidshank and normally extendingdiagonally thereto and engaging said longer lever arm of said dog in itsrecess, and resilient means normally urging said longer lever arm ofsaid dog in a predetermined direction about-its fulcrum to yieldablyhold said rotatable body against rotation in the opposite direction so1mg as a predetermined: torque is not applied thereto. a

6. An automatically releasing high torque wrench for use in applyinga-high torque to an element to .beturned, said wrench comprising: ahandle member having an atleast partially hollow head member at one endthereof, a rotatable body. mounted for free-rotation upon said headmember of said handle and adapted to be connected to the element to beturned by the wrench and having ratchet teeth. formed on itscircumferential portions, a shank slidably mounted within said handleand extending toga point adjacent to the hollow portion of said headmember, toggle mechanism connected to said shank and normally extendingdiagonallywith respect thereto and lying within said hollow portion ofsaid head member, and a first-class lever member pivotally mounted byits medial portion upon said head member and having a longer lever armand a shorter lever arm, said longer lever arm being engaged by saidtoggle mechanism, said shorter lever arm engaging the ratchet teeth onthe circumferential portions of said rotatable body, and resilient meansnormally-urging said rod toward said rotatable body and causing saidtoggle, mechanism to urge said longer lever arm of said lever member inapredetermined direction about its fulcrum to cause said. shorter leverarm to yieldably hold said rotatable body against rotation in theopposite direction so long as a predetermined torque is not appliedthereto, said shorter lever arm being swingableto non-engaging positionwhen such predetermined torque is applied to said body to permit thelatter-to thereafter rotate freely in the direction of the torquewithout being re-engaged by said shorter lever arm.

7. An automatically releasing high torque wrench comprising an atleastpartially hollow head member, a rotatable body mounted for freerotation in the ,hollowportion-of said head mem-' her and adaptedtoengage the element to be turned by the wrench, ahandle member rigidlysecured to said head member and having a central longitudinallyextending bore adjacent to and communicating with said-hollow'portion ofsaid head: member, a shank member mounted within said bore for limitedsliding movement therewithin and being constantly and yieldably urgedtoward said rotatable body, toggle mechanism swingably connected to theouter end of said shank member,- and a movable lever member interposedbetween said toggle member and said rotatable body, a portion of saidlever member being engaged by said toggle mechanism and being normallyurged, therebyto move in a predetermined direction about its fulcrum andanother portion of said lever member engaging said rotatable body toordinarily prevent its rotation in the opposite direction, said levermember when the wrench is in use moving its last mentioned portion tonon-engaging positionrelative to said rotatable body when apredetermined torque-is exceeded'to permit said rotatable body to rotatefreely in the direction of the torque without being re-engaged by saidlast mentioned portion.

8. An automatically releasing torque wrench comprising an at leastpartially hollow head member, a rotatable body mounted for free rotationin the hollow portion of said head member and adapted to engage theelement to be turned by the wrench, a handle member rigidly secured tosaid head member and having a central longitudinally extending boreadjacent to and communicating with said hollow portion of said headmember, a rod mounted within said bore for limited sliding movementlongitudinally of the handle, a toggle member swingably connected to theouter end of said rod and normally extending at an angle thereto andhaving an engaging element on the outer end portion of the same,resilient means constantly urging said rod toward said rotatable body, amovable lever member interposed between said toggle member and saidrotatable body, a portion of said lever member being engaged by theengaging element of said toggle member to urge said lever arm to move inone direction and the other portion of said lever member engaging saidrotatable body to ordinarily prevent its rotation in the oppositedirection, said lever member functioning to move said last mentionedportion to non-engaging position relative to said rotatable body when apredetermined torque is exceeded to permit said rotatable body to rotatefreely, and manual resetting mechanism connected to said lever memberand extending outwardly of said head member whereby said lever membermay be readily returned to engaging position with respect to said body.

OREN B. HARMES.

References Cited in the file of this patent UNITED STATES PATENTS

